Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue engage tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
Positioning the end effector is constrained by the trocar. Generally these endoscopic surgical instruments include a long shaft between the end effector and a handle portion manipulated by the clinician. This long shaft enables insertion to a desired depth and rotation about the longitudinal axis of the shaft, thereby positioning the end effector to a degree. With judicious placement of the trocar and use of graspers, for instance, through another trocar, often this amount of positioning is sufficient. Surgical stapling and severing instruments, such as described in U.S. Pat. No. 5,465,895, are an example of an endoscopic surgical instrument that successfully positions an end effector by insertion and rotation.
More recently, U.S. Pat. Ser. No. 10/443,617, “SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM” to Shelton et al., filed on 20 May 2003, describes an improved “E-beam” firing bar for severing tissue and actuating staples. Some of the additional advantages include affirmatively spacing the jaws of the end effector, even if slightly too much or too little tissue is clamped for optimal staple formation. Moreover, the E-beam firing bar engages the end effector and staple cartridge in a way that enables several beneficial lockouts to be incorporated.
Depending upon the nature of the operation, it may be desirable to further adjust the positioning of the end effector of an endoscopic surgical instrument. In particular, it is often desirable to orient the end effector at an axis transverse to the longitudinal axis of the shaft of the instrument. The transverse movement of the end effector relative to the instrument shaft is conventionally referred to as “articulation”. This articulated positioning permits the clinician to more easily engage tissue is some instances, such as behind an organ. In addition, articulated positioning advantageously allows an endoscope to be positioned behind the end effector without being blocked by the instrument shaft.
Approaches to articulating a surgical stapling and severing instrument tend to be complicated by integrating control of the articulation along with the control of closing the end effector to clamp tissue and fire the end effector (i.e., stapling and severing) within the small diameter constraints of an endoscopic instrument. Generally, the three control motions are all transferred through the shaft as longitudinal translations. For instance, U.S. Pat. No. 5,673,840 discloses an accordion-like articulation mechanism (“flex-neck”) that is articulated by selectively drawing back one of two connecting rods through the implement shaft, each rod offset respectively on opposite sides of the shaft centerline. The connecting rods ratchet through a series of discrete positions.
Another example of longitudinal control of an articulation mechanism is U.S. Pat. No. 5,865,361 that includes an articulation link offset from a camming pivot such that pushing or pulling longitudinal translation of the articulation link effects articulation to a respective side. Similarly, U.S. Pat. No. 5,797,537 discloses a similar rod passing through the shaft to effect articulation.
While these longitudinally controlled articulation mechanisms have provided certain advantages to surgical instruments such as for endoscopic stapling and severing, it is believed that an alternative articulation motion would provide additional design flexibility.
U.S. Pat. No. 5,405,344 teaches an endoscopic surgical instrument that, in the embodiment (shown in FIGS. 7–13), uses rotary motion about the longitudinal axis to articulate the end effector of the instrument in a conical motion. As taught, the articulating end effector uses a ball (convex member 174) attached to the end effector and a socket in a distal end of the hollow support tube 162. A hollow shaft 188 is bent into a “Z” shape and has a distal portion 198 that is bent to form at an angle to the longitudinal axis. Distal portion 198 is rotatably mounted within a passageway 178 extending into the ball or convex member 174 of the end effector. When the distal portion 198 is bent to the same angle as the passageway 178, the end effector and hollow shaft 188 can be assembled (in one position) aligning the longitudinal axis of the end effector with the hollow shaft 188. Rotation of the hollow shaft 188 from this alignment position articulates the end effector in a conical motion. As shown in FIGS. 10–13, the end effector both translates and rotates relative to the longitudinal axis. While providing articulation, the conical motion is not intuitive and requires rotation and repositioning of the surgical instrument to align the end effector with the tissue at a surgical site. What is needed is an articulation mechanism that can use rotation to articulate the end effector from side to side within a single plane relative to the longitudinal axis of the surgical instrument.
Consequently, a significant need exists for an articulating surgical instrument that incorporates an articulation mechanism that responds to a control motion other than a longitudinal translation.